Porthole



FIG. 1 is a front elevation view of a porthole showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof; and

FIG. 5 is a left end elevation view thereof, the right end being a mirror image of the left end shown herein.

The broken lines in FIGS. 3, 4 and 5 of the drawing are for illustrative purposes only. 

The ornamental design for a porthole, substantially as shown and described. 